Merge branch 'chris-use' into rotary-emb-custom-pos

tests/test_x_transformers.py

@@ -388,7 +388,8 @@ def test_neo_mlp():
     out = mlp(x)
     assert out.shape == (3, 7)
 
-def test_custom_alibi():
+@pytest.mark.parametrize('flash', (True, False))
+def test_custom_alibi(flash: bool):
 
     model = TransformerWrapper(
         num_tokens = 20_000,
@@ -397,7 +398,8 @@ def test_custom_alibi():
             dim = 512,
             depth = 2,
             heads = 8,
-            alibi_pos_bias = True
+            alibi_pos_bias = True,
+            attn_flash = flash
         )
     )
 
@@ -429,8 +431,8 @@ def test_custom_rotary_pos_emb():
     logits2 = model(x)
     assert torch.allclose(logits1, logits2)
 
-def test_custom_alibi_across_heads():
-
+@pytest.mark.parametrize('flash', (True, False))
+def test_custom_alibi_across_heads(flash: bool):
     model = Decoder(
         dim = 512,
         depth = 2,
@@ -439,6 +441,7 @@ def test_custom_alibi_across_heads():
         rel_pos_kwargs = dict(
             slopes = [1, 1]
         ),
+        attn_flash = flash
     )
 
     x = torch.randn(2, 4, 512)

x_transformers/attend.py

@@ -370,7 +370,7 @@ def flash_attn(
         # convert from bool to float
 
         if exists(attn_bias):
-            attn_bias = rearrange(attn_bias, 'h i j -> 1 h i j').expand(batch, heads, -1, -1)
+            attn_bias = attn_bias.expand(batch, heads, -1, -1)
 
             # if mask given, the mask would already contain the causal mask from above logic
             # otherwise, if no mask given but still causal, mask out alibi positional bias to a large negative number